Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
int H, W;
const int Hmax = 50;
string S[Hmax];

int main(){
	cin >> H >> W;
	for(int i=0; i<H; i++) cin >> S[i];

	queue<pair<int, int>> que;
	que.push({0, 0});
	vector<vector<int>> dist(H, vector<int>(W, 1e8));
	dist[0][0] = 0;
	while(!que.empty()){
		int x = que.front().first;
		int y = que.front().second;
		que.pop();
		int dx[] = {1, -1, 0, 0};
		int dy[] = {0, 0, 1, -1};
		for(int k=0; k<4; k++){
			int nx = x+dx[k];
			int ny = y+dy[k];
			if(nx<0||H<=nx||ny<0||W<=ny) continue;
			if(dist[nx][ny]<1e8 || S[nx][ny]=='#') continue;
			dist[nx][ny] = dist[x][y]+1;
			que.push({nx, ny});
		}
	}

	int nblack = 0;
	for(int i=0; i<H; i++){
		for(int j=0; j<W; j++){
			if(S[i][j]=='#') nblack++;
		}
	}

	if(dist[H-1][W-1]==1e8) cout << -1 << endl;
	else cout << H*W-nblack-(dist[H-1][W-1]+1) << endl;

	return 0;
}